Electric switch



Feb. 2 1926. 1,571,526

' R. c. MINTON ELECTRIC SWITCH Filed April 9, 1924 Patented Feb. 2, 1926.

UNITED TA ES PATENT OFFICE.

RICHARD CALDWELL MINTON, OF EAST IBOLDON, ENGLAND, ASSIGNOR TO A. REY- ROLLE & COMPANY LIMITED, or HEIBIBURN-ON-TYNE, ENGLAND, A BRITISH PANY. I

GOM-

ELECTRIC SWITCH.

. Application filed April 9, 1924. Serial No. 705,330.

To all whom it may concern:

Be it known that I, RICHARD CALDWELL MINTON, a subject of the King of England, and residing at East Boldon, 1n the county of Durham, England, have invented certain new and useful Improvements in Electric Switches, of which, the following is a specification.

This invention relates to electric sw tches and has particular reference to swltches which control a number of resistance sections such as are used in starting and regulating dynamo electric machines. It is sometimes necessary for certain operations to be performed such for example as the opening or closing of auxiliary circuits or the movement or control of interlocking mechanism at or near one or both ends of the travel of the contact arm or equivalent member of a regulating switch.

In a switch according to this invention a movable member is provided which is operated by the contact arm or the like when it is at or near the end of its travel, such movable member remaining in its new position and leaving the contact arm free to be moved back. Preferably the movable member is restored to its original position when the contact arm is returned to its initial place, that is to say the movable member is operated at eachend of the travel of the con tact arm.

In the accompanying drawings,

Figure 1 shows diagrammatically one construction of switch according to this invention, and

Figure 2 shows in perspective and by way of example a mechanical embodiment of a switch performing similar functions.

With reference first to Figure 1, A is the contactarm of a switch moving over contacts B between which are resistances C. Cooperating with this contact arm is a movable member somewhat like an inverted Y in shape. This member is pivoted as at D and comprises two arms D D and a stem stem D of the inverted Y member carries a switch F controlling an auxiliary circuit G and a second auxiliary circuit H is controlled by a switch J carried by the contact arm A itself.

A regulating switch of this kind is of particular advantage foruse with a motor converter in an automatic or semi-automatic substation. It is desirable for such a machine to have two definite resistances in the field circuit, one for starting and the other for running and. moreover for the regulating switch to be capable of varying the resistance in the circuit with thefield during running to vary the voltage of the machine.

These conditions are ing the resistance C as shown in Figure 1 in series with the field coil M of a motor converter N and by connecting the ends of the auxiliary circuit G across a definite portion of the resistance C and the switch arm A. In the starting position of the switch the gap in this auxiliary circuit G controlled by the switch F is closed as shown in Figure 1 and an auxiliary short-circuiting switch K is open. Thus the main portion of the resistance 0 is in circuit with the field coils of the converter. In this initial or starting position also the switch J closes a gap in the second auxiliary or starting circuit H which, as shown in Figure 1, includes the solenoid P which operates the main switch R controlling the A. C. supply mains S. The D. C. mains from the converter are shown at T.

lVhen the machine is run up and synchronized the switch K is closed (preferably by the automatic operation of the rotor short-circuiting gear) and the main portion of the resistance C is consequently shortcircuited. The first movement of the contact arm A away from its initial position breaks the second auxiliary or starting circuit H but further movement of the arm A has no effect until it reaches nearly the end of its travel for it is moving over the shortcircuited resistance sections C. At that point the contact arm reaches the contact B to which the end of the first auxiliary circuit G is connected and it then moves the arm I) and opens theswitch F thus breaking the short circuit across the main portion of the resistance but without altering the resist-ance in the field circuit. The contact arm A may now be ,moved in the reverse direction to insert more of the resistances G into the field circuit and may be moved freely backwards and forwards to vary that resistance and regulate the voltage ofthe machine.

The auxiliary circuit H is shown as having a second-gap controlled by a switch L which it opened would render the switch J inoperative, but this switch L like the switch K do not form in themselves part of the present invention and are not particularly described. I

Referring now'to Figure 2 the contact arm A of the switch is shown as mounted on a spindle A capable ofrotation by a hand wheel A this being a convenient and known type of construction. Instead of the switch J being mounted on the arm A it is operated by a projection A on the spindle A acting in conjunction with a spring-controlled lever J. Again the switch F controlling the auxiliary circuit G is operated through a pivoted spring-controlled lever F having a plate F on which are pins F and F The pin F projects downwards from the plate F in the path of a projection A mounted on the spindle A this pro ection A acting on the pin F to close the switch. The pin F 3 projects upward from the plate F in the path of another arm or pro ection A and these two members cooperate to open the switch F when the hand wheel A has been rotated to bring the switch arm A from its initial position as shown to the end of its travel, 'i. e. to the contact B where the auxiliary circuit G to the left of Fig-' ure- 2 is connected to the resistances C.

Figure 2 is given as showing a convenient mechanical construction for a switch ac-" cording to this invention suitable for fulfilling the functions described with reference to the switch shown diagrammatically in Figure 1 c In the case of an automatic substation previously referred to, arrangements are preferably made whereby the switch may be locked in its initial position when the station shuts down so that the gaps in the circuits controlled by the switches J and F are closed. This locking may be accomplished in any convenient way say by mechanism which prevents the rotation of the hand wheel A. f

The description above given of the particular application of a regulating switch according to this invention is by way of examle only. I

The-details of construction may be varied and' instead of the auxiliary circuits mentioned mechanical interlocking devices may be arranged operated by the switch arm or the mechanism which moves it at its initial an'dfinal positions. Again more than one movable member'operated by the switch arm or its equivalent may be employed so that intermediate operating positions may be obtained.

What. I claim as my invention and desire to secure by Letters'Patent is:-

1. In a resistance-regulating switch the combination of a resistance, a plurality of contacts connected to said resistance in intervals or steps, a main contact-making member adapted to move over said contacts, an auxiliary switch adapted to be closed when the main contact-making member is in its initial position, and a, second auxiliary switch adapted to be opened when the main contactmaking member reaches the end of its travel and to' be closed when the main contact-making member is in its initial position.

2. In a resistance-regulating switch the combination of a resistance, a plurality of contactsconnected to said resistance in intervals or steps, a main contact-making member adapted to move over said contacts, an auxiliary switch adapted to be closed when the main contact-making member is in its initial position and opened when the arm is in any other position, a short circuiting circuit connected across a portion of the resistance and the main contact-making member and a second auxiliary switch in such circuit ada ted to be closed when the main contact-ma ing member is in its initial position and opened when said main contactmaking member reaches the end of its travel. I

3. In a resistance-regulating switch the combination of a resistance, a plurality of contacts connected to said resistance in intervals or steps, a main contact-making member adapted to move over said contacts, a starting circuit for a motor converter, an auxiliary switch in said starting circuit adapted to be closed when the main contactmaking member is in its intial position and to be opened when the main contact-making member leaves that position, a circuit connected across a portion of the resistance and the main contact-making member, a second auxiliary switch in said circuit, act-ing when closed to short-circuit the portion of the resistance to which said circuit is connected, and means for opening said second auxiliary switch when the main contact-making mem ber has passed over the short-circuited poring circuit for a motor converter, an auxiliary switch in said starting circuit, an operative connection between the spindle and said auxiliary switch acting to close said switch when the main switch arm is in its initial position, a spring acting to open said auxiliary switch when the main switch arm leaves its initial position, a circuit connected to a portion of said resistance, a second auxiliary switch in said circuit, an operative connection between the spindle and said second auxiliary switch acting to closesaid switch and short-circuit the connected portion of the resistance when the main switch arm is in its initial position, and an opera tive connection between the spindle and said second auxiliary switch acting to open said switch when the main switch arm has passed 15 over the short-circuited portion of the IESlS- tance so that the said portion can be brought into operation by a backward movement of the main switch arm.

In testimony whereof I have signed my 20 name to this specification.

RICHARD CALDWELL MINTON. 

